Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources in this section. This section needs additional citations for verification. In various forms, other designs are under development by MIT, University of California at Berkeley, General Atomics (U.S.), the Dutch company Romawa B.V., Adams Atomic Engines, Idaho National Laboratory, X-energy and Kairos Power. The AVR design was licensed to South Africa as the PBMR and China as the HTR-10, the latter currently has the only such design in operation. This system was plagued with problems and political and economic decisions were made to abandon the technology. The concept was first suggested by Farrington Daniels in the 1940s, said to have been inspired by the innovative design of the Benghazi burner by British desert troops in WWII, but commercial development did not take place until the 1960s in the German AVR reactor by Rudolf Schulten. Because of its design, its high temperatures allow higher thermal efficiencies than possible in traditional nuclear power plants (up to 50%) and has the additional feature that the gases do not dissolve contaminants or absorb neutrons as water does, so the core has less in the way of radioactive fluids. īecause the reactor is designed to handle high temperatures, it can cool by natural circulation and still survive in accident scenarios, which may raise the temperature of the reactor to 1,600 ☌ (2,910 ☏). Some examples of this type of reactor are claimed to be passively safe.

Other coolants such as FLiBe (molten fluoride, lithium, beryllium salt) ) have also been suggested for implementation with pebble fuelled reactors. In the PBR, thousands of pebbles are amassed to create a reactor core, and are cooled by a gas, such as helium, nitrogen or carbon dioxide, that does not react chemically with the fuel elements. These TRISO fuel particles consist of a fissile material (such as 235U) surrounded by a ceramic layer coating of silicon carbide for structural integrity and fission product containment. 6.7 cm or 2.6 in in diameter) are made of pyrolytic graphite (which acts as the moderator), and they contain thousands of micro-fuel particles called tristructural-isotropic (TRISO) particles. The basic design of pebble-bed reactors features spherical fuel elements called pebbles.

High temperature reactor meltdown why